Modified pullulan unlocks efficient polyplex-mediated gene silencing following nebulization

Area of Science:

• Biomaterials Science
• Nanotechnology
• Gene Therapy

Background:

• Pullulan (PULL) is a natural polymer with potential for pulmonary siRNA delivery.
• Tailoring PULL's molecular weight and functionalization is key to optimizing its carrier properties.

Purpose of the Study:

• To engineer pullulan-based amphiphilic copolymers for inhalable siRNA delivery.
• To evaluate the physicochemical properties, aerosol performance, and biological efficacy of these novel carriers.

Main Methods:

• Controlled acidic hydrolysis to reduce PULL molecular weight.
• Functionalization of PULL with 1,2-bis(3-aminopropylamino)ethane (bAPAE) and all-trans-retinoic acid (Ret).
• Characterization of polyplexes, nebulization, aerodynamic assessment, and in vitro gene silencing studies.

Main Results:

• Successfully synthesized PULL-bAPAE-Ret amphiphilic copolymers with suitable buffering capacity and self-assembly behavior.
• Achieved efficient siRNA complexation, controlled release, and RNase protection.
• Nebulization demonstrated excellent recovery (>90%) and suitable aerodynamic properties (~2 μm MMAD, >80% FPF) for deep lung deposition.
• In vitro studies showed high cytocompatibility, enhanced cellular uptake, improved endosomal escape, and superior gene silencing efficiency (~38% luciferase reduction).

Conclusions:

• Rationally engineered pullulan-amphiphilic copolymers are promising inhalable carriers for siRNA delivery.
• These formulations combine tunable physicochemical properties with significant biological efficacy for pulmonary gene silencing.